<?php
class Foo
{
    public function sneeze()
    {
        echo 'achoooo';
    }
}

abstract class Bar extends Foo
{
    public abstract function hiccup();
}

class Baz extends Bar
{
    public function hiccup()
    {
        echo 'hiccup!';
    }
}

$baz = new Baz();
$baz->sneeze();
$baz->hiccup();
?> 
